How are plants modified to be pest resistant?

We put this question to Dr Jim Haseloff, from Cambridge University:

Jim - Organic farmers actually use bacteria - the Bacillus thuringiensis bacterium which has a protein which affects the gut of specific insects and that protein, of course, is encoded in the gene and that gene can be then transferred to plants using genetic engineering techniques. So it's essentially a surgical procedure of isolating the particular gene using a natural bacterium to transfer that into a plant and then once it's in there, it's used as a gene that's for breeding.

Chris - So presumably, with synthetic biology, what one would do is to say "rather than take that toxin from a bacterium, what would be better would be to study the organisms that we want to make the plant resistant to, and then find our own way of making the plant resistant" and put some kind of specific thing into the plant that will be even better than what a bacterium toxin could do for us.

Jim - That's certainly feasible in the longer term. I think most of the emphasis at this point is on better engineering using existing systems, existing parts from what we know in the biological world and rearranging their delivery inside say, for example a crop system, where you might get around some of the issues we're talked about earlier in the program where you've got some insects which are immune to these very specific toxins and can escape. So you can imagine a second element that would deal with that for example.